The present invention relates to a table comprising a table body, a cradle provided on the table body and driving means for driving the cradle, and an MR (magnetic resonance) apparatus having the table.
In an MR apparatus, a table for carrying an object under study into a magnet is comprised of a table body, a cradle provided on the table body, and driving means for driving the cradle.
For a driving source of the driving means, a pulse motor is employed which, when supplied with electric pulses, is rotated by a constant angle for each input pulse.
However, when the pulse motor is driven during scanning by the MR apparatus, the input pulses give rise to noises and adversely affect a captured image.
Therefore, driving of the cradle and scanning cannot be simultaneously performed, That is, imaging cannot be performed while driving the cradle.
Thus, when an extended region is to be imaged, the scanning should be suspended to move the cradle, which leads to a problem that an imaging time per object under study is protracted.
Moreover, since the pulse motor comprises magnets and coils, it cannot be accurately driven in a high-strength magnet field.
This also affects a captured image.
Accordingly, when the pulse motor is employed, it must be disposed at a place that is not affected by the magnetic field, which leads to another problem that a mounting position for the pulse motor is restricted.
It is therefore an object of the present invention to provide a table and an MR apparatus which allows moving of a cradle and scanning to be simultaneously performed.
It is another object of the present invention to provide a table and an MR apparatus which imposes no restrictions on a mounting position for a driving source.
In accordance with a first aspect of the invention, there is provided a table comprising a table body, a cradle provided on the table body, and driving means for driving the cradle, wherein the driving means has a driving source utilizing fluid pressure.
In accordance with a second aspect of the invention, there is provided an MR apparatus having a table comprising a table body, a cradle provided on the table body and driving means for driving the cradle, wherein the driving means of the table has a driving source utilizing fluid pressure.
By employing a driving source utilizing fluid pressure as driving means for driving a cradle, noises which adversely affect a captured image are not generated during driving of the cradle.
Therefore, moving of the cradle and scanning can be simultaneously performed.
The fluid pressure may be, but is not limited to, liquid pressure or as pressure.
In addition, the driving source utilizing the fluid pressure may be, but is not limited to, a hydraulic motor, a hydraulic cylinder or an air cylinder, for example.
In accordance with a third aspect of the invention, there is provided the table as described regarding the first aspect, wherein the driving source is a hydraulic motor.
When the moving amount for a driven object is small, a hydraulic cylinder or an air cylinder is preferable because the driving means can be simplified, and when the moving amount for a driven object is large, a hydraulic motor is preferable because the driving means can be made compact.
While the fluid may be gas or liquid, liquid, which is an incompressible fluid, provides better controllability.
Therefore, in the present table and MR apparatus, a hydraulic motor is preferable for the driving source insofar as the driving means can be made compact and the driving means can provide good controllability.
In accordance with a fourth aspect of the invention, there is provided the table as described regarding the first or third aspect, wherein the driving source is made of a non-magnetic material.
In accordance with a fifth aspect of the invention, there is provided the MR apparatus as described regarding the second aspect, wherein the driving source is made of a non-magnetic material.
By making a driving source out of a non-magnetic material, it can be accurately driven even in a high-strength magnetic field, and it does not affect a captured image.
Accordingly, a mounting position for the driving source is not restricted.
Thus, the present invention can provide a table and an MR apparatus which allows moving of a cradle and scanning to be simultaneously performed.
Moreover, the present invention can provide a table and an MR apparatus which imposes no restrictions on a mounting position for a driving source.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.